A shoulder joint consists of a ball-and-socket type coupling of the humerus to the scapula. The humerus forms the ball, and the socket is formed at the glenoid cavity of the scapula. Injury or disease to the joint often results in destruction or deterioration of the head of the humerus, leading to pain and a corresponding loss of mobility and function. In such cases, it is often necessary to provide a replacement joint surface, i.e., a prosthesis, for the head of the humerus that mates with the glenoid cavity.
The proper alignment of the prosthesis is generally useful to effective performance of the replacement procedure. Typically, the position of the mount is adjusted until the desired position is achieved. The mount is fixed in the desired position and the prosthesis is then secured onto the mount.
However, conventional mounts provide only a limited range of adjustment, typically allowing only two degrees of freedom, i.e., linearly along an X-axis and Y-axis. The devices that do have more degrees of freedom require multiple trials and a fixture to be used away from the surgical site for proper alignment of the prosthesis to the humerus.
Further, even upon locking the device in a desired position, conventional mounts may not hold the desired position. This is especially true when force is exerted, e.g., hammering the prosthesis to secure its placement on a mount.
There remains a need for mounting systems and methods that permit a wide range of adjustment of a humeral head prosthesis while enabling the mount, and attached prosthesis, to remain securely fixed in a desired position.